Roller assembly



April 1968 E. w. FERDIG I 3,378,233

ROLLER AS SEMBLY Filed July 19, 1965 4 Sheets-Sheet 1 .7-- f! f -Z INVENTOR.

April 16, 1968 E. w. FERDIG 3,

' ROLLER ASSEMBLY Filed July 19, 1965 I 4 Sheets-Sheet r:

INVENTOR April 16, 1968 E. w. FERDIG ROLLER ASSEMBLY 4 Sheeis-Sheet R 4. 1 m M WM w M w WW Filed July 19, 1965 April' -16 1968 E. W.FERDQIG ,3

ROLLERASSEMBLY 7 Filed July 19, 1965 A {Sheets-"Sheet 4 INVENTOR.

United States Patent Ofiice 3,378,233 Patented. Apr. 16, 1968 3,378,233 ROLLER ASSEMBLY Earl W. Ferdig, Burbank, Calif., assiguor to George F. McMurray, Burbank, Calif. Filed July 19, 1965, Ser. No. 473,051 4 Claims. (Cl. 254-192) ABSTRACT OF THE DESCLOSURE A roller assembly having a ribbed shaft and a pair of slotted flanges integrally formed on opposite ends of the shaft. A roller is captively and rotatably mounted on the shaft between the flanges. Inclusion of the slots in the flanges permits the assembly to be manufactured in a single molding operation.

Background of the invention This invention relates to an improved roller assembly, and to a mold for making the roller assembly.

Roller assemblies are used in many different forms and in many different applications. They may take the form of wheels, pulleys, bearings, etc. Such assemblies typically include a roller, a shaft or axle through the roller, and a pair of flange or sidewalls secured to opposite end of the shaft for retaining the roller on the shaft and for proiding a convenient means for mounting the roller assembly to another structure.

Roller assemblies have typically been produced in the past by separately fabricating the several component parts, which are then assembled in an additional production step. The additional step is time consuming and expensive, and it is desirable to fabricate the entire roller assembly in a single production step in order to meet the widespread demand for low-cost roller assemblies.

This goal has been partially met by the roller assemblies described in my co-pending applications Ser. No. 231,328 filed Oct. 15, 1962, now Patent No. 3,206,992 issued Sept. 21, 1965 and Ser. No. 272,285 filed Apr. 11, 1963, now Patent No. 3,255,997 issued June 14, 1966. These applications describe plastic roller assemblies which are molded in a single production step, the units emerging from the mold in ready-to-use condition. That is, a freespinning roller is formed around a shaft having flanges to make the roller captive on the shaft, the entire assembly being formed in a single molding operation.

These molded roller assemblies have proved highly satisfactory in many applications. There remains, however, a demand for roller assemblies incorporating flanges which may be of widely diversified shapes and which are integral with the shaft to provide strength and rigidity. It is also desirable to produce such roller assemblies in a molding process which does not require deformation of a flange when the assembly is removed from the mold. Such a process is useful because it permits a simpler molding procedure and provides extended mold life.

The roller assembly of this invention meets these goals and provides a simple, integral structure which can be molded in many shapes and from a variety of materials. The roller assembly, and the process by which the assembly is formed is described in terms of an injectionmolded plastic structure. It is to be understood, however, that the roller assembly is adaptable to die casting and can therefore be fabricated from metal if desired.

Briefly stated, the improved roller assembly includes a roller having an axial opening therethrough. A shaft is disposed in the opening. A pair of flanges are disposed on opposite sides of the roller and are integral with opposite sides of the shaft. Each flange has an arcuate slot therethrough, the solt being substantially in alignment with a portion of the shaft periphery.

The arcuate slot in each flange allows a mold member to project through the flange to extend to the inner face of the other flange during the molding of the assembly. Several members can thus be inserted through the two flanges to form a hollow cylindrical shell between the flanges, the inside of the shell serving as a cavity for forming the shaft. The Outside of the cylindrical shell serves to form the interior surface of the roller. The roller and shaft are thereby separated, even though formed in the same molding operation, allowing the roller to spin freely about the shaft when the cylindrical-shell members of the mold are removed.

In a preferred form of the invention, the cylindricalshell members of the mold are shaped. to form raised lon gitudinal ribs on the shaft surface parallel to the shaft axis. The clearance between the effective outer diameter of the shaft and the roller inner surface is thereby reduced, providing a closer running fit between these parts. in this manner, the cylindrical'shell members of the mold may be very thin, with structural stren th being added by the ribbed portions of the shell which form the depressions between the ribs on the shaft.

In another form, the roller assembly may be fabricated with a web section joining the ends of the two flanges. Thus a continuous, closed structure comprising the integrally formed shaft, flanges and web is provided, with the roller cast in place around the shaft. The web section provides a convenient mounting surface for certain applications of the roller assembly. For example, the roller may be formed in the shape of a wheel, and the web section used to secure the wheel to another surface.

In still another form, the roller assembly can be fabricated as a pulley. Such pulleys are inexpensive to produce and are especially useful as cord tension pulleys for draperies.

A mold for casting the roller assembly includes a pair of blocks, each of which has an outwardly extending shell. The blocks are disposed in spaced-apart relation whereby the two shells overlap and seat on each other to define a shaft cavity. A pair of inserts are disposed between the spaced-apart blocks and around the seated shells to define a roller cavity and a pair of flange cavities. The shaft cavity, roller cavity, and flange cavities are interconnected whereby a molding material injected into any cavity will flow into all other cavities.

These and other aspects of the invention will be explained by reference to the attached drawings in which:

FIG. 1 is a front elevation of a roller assembly;

FIG. 2 is a side elevation taken on line 2-2 of FIG. 1;

FIG. 3 is a side elevation taken on line 33 of FIG. 1;

FIG. 4 is an exploded perspective view of the roller assembly;

FIG. 5 is a front elevation of a roller assembly with a web section joining the flanges;

FIG. 6 is a side elevation of the roller assembly shown in FIG. 5 showing longitudinal ribs on the shaft;

FIG. 7 is a fragmentary perspective view, partly in section, of the roller assembly shown in FIGS. 5 and 6;

FIG. 8 is a plan view of a pulley formed in accordance with the invention;

FIG. 9 is a plan view of the opposite side of the pulley shown in FIG. 8;

FIG. 10 is a side elevation of the pulley with the frame in a closed position;

FIG. 11 is a side elevation of the pulley with the frame in an open position;

FIG. 12 is a view taken on line 12-l2 of FIG 9;

FIG. 13 is a perspective view of a mold for forming the pulley shown in FIGS. 8 12, the mold being shown in an open position;

FIG. 14 is a perspective View of the mold in a closed position;

FIG. 15 is a fragmentary cross-section taken on line 15-45 of FIG. 16, showing a portion of the mold forming the shaft cavity;

FIG. 16 is a view taken on line 16-16 of HG. 15; and

FIG. 17 is a cross-section of the closed mold taken on line i7-1l7 of FIG. 14.

Referring to FIGS. l4, a roller assembly 26 according to this invention includes a roller 22 having an axial opening 23 therethrough. A shaft 24 is disposed in the opening. Opening 23 has a larger diameter than shaft 24 such that an annular clearance space exists between the roller and shaft. A pair of flanges 2d and 27 are disposed on opposite sides of the roller. Each flange is secured to and formed integrally with the shaft.

Flange 26 has a susbtantially semi'circular slot 2 therethrough. Flange 2.7 has a similar substantially semicircular slot 39 therethrough. Each slot is substantially in alignment with a portion of the shaft outer periphery and is centered on the axis of the shaft to be coaxial therewith. The slots are oppositely oriented to form the equivalent of an annular gap around the shaft when the assembly is viewed from the side as suggested in FIG. 3. Preferably each slot extends slightly more than 180, whereby the oppositely oriented slots have a slight overlap.

Another form of the invention is shown in FIGS. 57. A roller assembly 31 includes a roller .12 disposed around a shaft 34. A pair of flanges and 37 are disposed on opposite sides of the roller. The flanges are secured to and formed integrally with the shaft. A web 39 joins and is formed integrally with the ends of the flanges.

A multiplicity of raised longitudinal ribs 41 are disposed on the outer periphery of shaft These ribs serve to reduce the clearance between the shaft and the roller to insure smooth operation, and also to allow the use of a structurally strong mold. The ribs could of course also be disposed on the inner surface of the roller to extend toward a smooth-surface shaft.

Flange 36 has a substantially semi-circular slot 43 thcrethrough, the slot being substantially in alignment with a portion of the shaft periphery. Flange 3'7 has a similar slot 4%, the two slots being oppositely oriented as suggested in FIG. 6. Preferably, each slot extends slightly more than 180 whereby the oppositely oriented slots have a slight ovenap.

In both of the assemblies described above, it will be noted that the roller is made captive on the shaft by the flanges. Forming of the entire roller assembly in a single molding operation is made possible by the flange slots. These slots permit introduction of thin, shell lihe mold members which separate the interior of the roller from the shaft. The use of slightly overlapping slots allows the mold members to be tapered to insure easy mold separation. When the roller assembly is removed from the mold, the assembly is ready for use without any further manufacturing steps.

FIGS. 8-12 show another form of the invention wherein a roller assembly is fabricated as a pulley The pulley includes a U-shaped frame 52 having a pair of spacedapart flanges 5'4- and 55 joined at one end by a transverse web 57. A shaft 59 is disposed between and formed integrally with flanges 54 and A roller having a concave surface 62- is disposed around the shaft between the flanges.

Flange 54- has a substantially semi-circular slot 54 therethrough in substantial alignment with a portion of the periphery of shaft 5%. Flange has a similar semicircular slot 65 therethrough in substantial alignment with a portion of the shaft periphery. As shown in FIG. 9, the two slots are oppositely oriented whereby the entire outer periphery of the shaft is accessible through the slots in the flanges.

Shaft 59 has a concave portion 67 in each end. The function of the concave portion is to conserve the quantity of material used to mold the shaft. Shaft 59 may also be provided With raised longitudinal ribs as already suggested in FIGS. 6 and 7. For clarity of illustration, these ribs are omitted in FIGS. 812.

Flange 54 carries an inwardly extending button 70 on the end opposite the transverse web. A button recess 71 is defined by an inwardly extending boss 72 on flange opposite the button. The button recess has a stepped bone with a first relatively short section 74 of slightly smaller diameter than the button. The remainder of the button-recess bore is an enlarged section 75 which is substantially the same diameter as the button.

A pair of inwardly extending spacers 78 and 79 are integrally formed on the inner opposing faces of the flanges between the roller and the button and buttonrecess boss. A stiffening rib 80 is integrally formed on flange 55 between the boss and spacer 79. An elongated retaining clip 81 is formed integrally at one end with the end of the boss adjacent the button. The clip extends toward but stops short of the spacers. A stop ball 82 is integrally formed on the end of the clip adjacent the spacers.

The pulley may be cast from a variety of materials but is especially suitable for molding from a plastic such as nylon. Use of the pulley as a drapery cord tension pulley will now be described, although it is to be understood that the pulley has many other applications.

With the button end of the U-shaped frame open as shown in FIG. 11, a drapery pull cord 85 (shown in phantom) is slipped between the button and button-recess boss to pass between spacers 78 and 7 to seat on the concave surface of roller 61. The loop of a retaining spring 87 (shown in phantom) is then slipped between the button and button-retaining boss to pass around the retaining clip to seat on the boss.

The cord and spring are locked in place by squeezing together the flanges to force the button into the buttonretaining recess. This closed position of the pulley assembly is illustrated in FIG, 10, which also shows how the spacers 78 and '79 abut each other to maintain the flanges in a spaced-apart condition, preventing binding of the roller on the flanges. The pulley assembly is thus locked in place and ready for service in the drapery-cord system.

The invention is not restricted to the three roller-assembly configurations described above. Many other configurations may be made in accordance with the invention. For example, the roller surface may be of any convenient curvature and the flanges may be formed to provide a variety of convenient mounting methods. The provision of slots in the flanges in substantial alignment with the shaft surface permits the roller assembly to be molded or cast in a single operation.

A mold 9t) suitable for forming the pulley assembly just escribed is illustrated in FIGS. 13l7. The mold is shown in an open position (for ejecting a finished pulley assembly) in FIG. 13, and in a closed position (ready for forming a pulley assembly) in FIG. 14. The mold includes a base block 92, a cover block 93, and a pair of inserts 5 and Arrows 98 show how the base block, cover block, and inserts move toward each other from the open to closed position.

Base block 92 has a circular opening 100 therethrough, best seen in FIGS. 15 and 17. A thin, semi-cylindrical hollow shell 192 is secured to the base block adjacent the periphery of the hole 139, and extends toward cover block The shell has two longitudinally extending edges 103 which are tapered as shown in FIG. 15 to insure easy mold separation. A econd thin, semi-cylindrical hollow shell is secured to the cover block and extends toward the base block. Shell has two longitudinally extending edges 196 which are tapered to match the taper on edges 193.

FIG. shows how the two shells seat on one another when the mold is in a closed position (inserts 95 and 96 are deleted in FIG. 15 for clarity). Edges 103 and 106 fit snugly against each other, the two shells thus forming a continuous cylindrical shell 1113 as best seen in FIG. 16. The interior of cylindrical shell 168 forms a shaft cavity 109. The exterior of cylindrical shell 198 defines the inner surface of a roller cavity 111 as best seen in FIG. 17.

As shown in FIGS. 13, 15 and 16 (but deleted in FIG. 17 for clarity), the inner surfaces of shells 182 and 165 define a plurality of longitudinal grooves 111 for forming ribs on the shaft surface. The grooves could be relocated on the outer surface of the shell if it is desired to form ribs on the inner surface of the roller for rotation around a smooth-surface shaft.

When the mold is in a closed position, the end of shell 102 stops short of cover block 93 to define a gap 112 as shown in FIG. 15. Similarly, shell 1G5 stops short of base lock 92 to define a gap 13 These gaps permit free flow of plastic through the mold whereby the roller-assembly flanges and shaft are formed as an integral structure.

The base block has a recessed wall 115 around the base of shell 162. This recessed wall defines one side of a first flange cavity 116. The cover block has a recessed wall 113 around the base of shell 165. Recessed wall 118 defines one side of a second flange cavity 119. The two flange cavities are best seen in P16. 17.

Inserts 95 and 96 have recessed walls 121 in the surfaces which face the base block. Recessed walls 121 form a second wall of first fiange cavity 16. The opposite faces of inserts 95 and 96 which face the cover block have recessed walls 122. Recessed Walls 22 form a second wall of second flange cavity 119.

The abutting edges of inserts 95 and 96 include semicircular recesses whereby the blocks fit together snugly around assembled cylindrical shell 168 to form an annular wall 125 which defines the outer surface of roller cavity 110. The annular wall is inwardly convex to form the concave surface of the pulley roller. Recessed wall 121 of insert 95 has several small openings 127 whereby fluid plastic may flow from flange cavity 116 into the roller cavity during the molding operation.

A hollow, close-fitting ejection sleeve 129 is slidably disposed in opening 190 of base block 92. A first stationary core 131 makes a close fit within ejection sleeve 12). The stationary core has a rounded end which extends slightly beyond the inner end of the ejection sleeve. A

second stationary core 132 with a rounded and is secured to and extends from the inner face of cover block 93. The cores (best seen in FIGS. 13 and 17, and omitted in FIGS. 15 and 16 for clarity) extend into shaft cavity 169 to define the concave shaft ends in the molded pulley assembly.

The two inserts are recessed to form a web cavity 135 which connects the flange cavities 116 and 119. The inserts are also recessed to form a button cavity 137, a boss cavity 138, a clip and stop-ball cavity 139, a stiffening rib cavity 140, and a pair of spacer cavities 141. A hollow, close-fitting ejection sleeve 142 is slidably disposed in a hole through base block 92 in alignment with the boss cavity. A necked-down stationary core 143 is disposed within and extends beyond ejection sleeve 142 to define the inner surface of the boss cavity.

A filling cavity 145 is defined by the abutting inserts, and is in alignment with a filling passageway 146 in the cover block and an ejection pin 148 slidably disposed through the base block. A slanted, tapered portion of filling cavity 145 is in communication with web cavity 135.

To cast a pulley assembly, the mold is assembled in a closed position as shown in FIG. 14, and a source of fluid plastic is connected to filling passageway 146. The mold would typically be mounted on an injection molding ma chine (not shown) which would automatically position the several mold blocks, inserts, stationary cores and the ejection pin and sleeves.

Plastic is then injected through the filling passageway into the web and flange cavities. The fluid plastic circulates through the flange cavities to fill all the other cavities in the mold. Holes 127 provide an entrance for the fluid plastic from flange cavity 116 into the roller cavity.

When the plastic has solidified, cover block. 93 is backed away from the mold, and ejection pin 148 is moved to eject the flash material which has formed in filling cavity 145. The flash material is severed from the web portion of the molded pulley by this operation. Inserts and 96 are then moved away from each. other to expose the completed pulley. As insert 95 is moved, the slender threads of hash material extending through holes 127 are severed, permitting the roller to move freely around the pulley shaft.

Ejection sleeves 129 and 142 are then moved through the base block, forcing the completed pulley assembly out of the mold. The base block, cover block and inserts may then be moved together to place the mold in a closed position in readiness for the next molding operation.

While the mold just described is designed for production of pulley assemblies, it is to be understood that the invention is not restricted to this specific mold. The general principles of the invention may be incorporated in many different styles of molds which would be used to produce the various forms of roller assemblies already described.

I claim:

1. The combination comprising a roller having an axial opening therethrough; a shaft disposed in the opening to define an annular clearance space between the shaft and roller; and a pair of flanges disposed on opposite side of the roller and integrally formed on opposite ends of the shaft, the flanges and shaft being a single integral, molded structure, the flanges having arcuate slots therethrough, each slot being substantially aligned wit-h a portion of the shaft periphery and opening directly into a portion of the annular clearance space, the flange slots together providing access through the flanges to the entire periphery of the shaft and the entire annular clearance space.

2. The combination defined in claim 1 in which the flange slots are substantially semicircular in shape and are coaxial with the shaft, the two slots being overlapping and oppositely oriented.

3. The combination defined in claim 2 in which the annular space is defined by an outer surface of the shaft and an inner surface of the roller, and one of said surfaces defines a plurality of integrally formed axially extending raised ribs.

4. The combination defined in claim 2 and further co prising a transverse web member spaced from the shaft and secured to the flanges to form a U-shaped frame, the web member, flanges and shaft being a single integral molded structure, the roller being integral and further being made captive on the shaft by the flanges.

References Cited UNITED STATES PATENTS 3,255,997 6/1966 Ferdig 254-192 FOREIGN PATENTS 591,771 9/1932 Germany.

ANDRES H. NIELSEN, Primary Examiner. EVON C. BLUNK, Examiner.

H. C. HORNSBY, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,378 ,233 April 16, 1968 Earl W. Ferdig It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1 line 26,"flange" should read flanges '8' Column 2 line 1, ','so1t" should read slot 5: Column 5, line 21, "13";should read 113 line 32, 'l6" should read 116 Column 6, line 36 "side" should read sides Signed and sealed this 2nd day of September 1969.

(SEAL) Attest: Edward M. Fletcher, Jr. WILLIAM E. SCHUYLERfIR Attesting Officer Commissioner of Patents 

